TargetsetupPage: Fix crash

The case looks like this:
Two kits on the targetsetuppage.
- Already existing kit, selected
- Temporary kit not selected

Switch reset() and setupProject() to the order they had before
the TargetSetupPage generalization.

Task-number: QTCREATORBUG-10417

Change-Id: I51cfb1e01193c57e06aebeaa8defa11809e24c50
Reviewed-by: Mitch Curtis <mitch.curtis@digia.com>
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>